Tin oxide thin film spacers in semiconductor device manufacturing

Abstract

Thin tin oxide films are used as spacers in semiconductor device manufacturing. In one implementation, thin tin oxide film is conformally deposited onto a semiconductor substrate having an exposed layer of a first material (e.g., silicon oxide or silicon nitride) and a plurality of protruding features comprising a second material (e.g., silicon or carbon). For example, 10-100 nm thick tin oxide layer can be deposited using atomic layer deposition. Next, tin oxide film is removed from horizontal surfaces, without being completely removed from the sidewalls of the protruding features. Next, the material of protruding features is etched away, leaving tin oxide spacers on the substrate. This is followed by etching the unprotected portions of the first material, without removal of the spacers. Next, underlying layer is etched, and spacers are removed. Tin-containing particles can be removed from processing chambers by converting them to volatile tin hydride.

What is claimed is: 
     
       1. A method of processing a semiconductor substrate, the method comprising:
 (a) providing a semiconductor substrate having an exposed layer comprising a first material and at least one protruding feature comprising a second material that is different from the first material; and 
 (b) depositing a SnO 2  layer over both the first material and the second material, including sidewalls of the at least one protruding feature, wherein the first material and the second material are selected such that a ratio of an etch rate of the first material to an etch rate of SnO 2  is greater than 1 for a first etch chemistry, and a ratio of an etch rate of the second material to an etch rate of SnO 2  is greater than 1 for a second etch chemistry, and wherein the depositing comprises sequentially exposing the first material and the second material of the semiconductor substrate to a tin-containing precursor and an oxygen-containing precursor; 
 (c) after depositing the SnO 2  layer, completely removing the SnO 2  layer from horizontal surfaces of the semiconductor substrate without completely removing the SnO 2  layer covering the sidewalls of the at least one protrusion; and 
 (d) after removing the SnO 2  layer from horizontal surfaces of the semiconductor substrate, completely removing the at least one protrusion using the second etch chemistry, without completely removing the SnO 2  layer that was covering the sidewalls of the at least one protrusion, thereby forming SnO 2  spacers. 
 
     
     
       2. The method of  claim 1 , wherein the depositing comprises exposing the first material and the second material of the semiconductor substrate to the tin-containing precursor, having a formula
   R x −M−A (4-x)  
 
 wherein x can be 0, 1, 2, or 3; 
 M is tin; 
 R can be selected from an aliphatic substituent, heteroaliphatic substituent, or any combination thereof; and 
 A is YR′z wherein Y can be selected from N or 0;
 z is 1 when Y is O, and z is 2 when Y is N; and
 each R′ can be independently selected from an aliphatic substituent, heteroaliphatic substituent, or any combination thereof. 
 
 
 
     
     
       3. The method of  claim 1 , wherein tin in the tin-containing precursor is selected from the group consisting of tin(II) and tin (IV). 
     
     
       4. The method of  claim 2 , wherein a first R′ of YR′z is same as a second R′ of YR′ z . 
     
     
       5. The method of  claim 2 , wherein a first R′ of YR′ z  is different from a second R′ of YR′ z . 
     
     
       6. The method of  claim 5 , wherein the tin-containing precursor is tetrakis(ethylmethylamino) tin. 
     
     
       7. The method of  claim 2 , wherein each of R and R′ can independently be selected from an alkyl group, an alkenyl group, an alkynyl group, or a combination thereof. 
     
     
       8. The method of  claim 7 , wherein the alkyl group is methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, tert-butyl, or combination thereof. 
     
     
       9. The method of  claim 1 , wherein the tin-containing precursor is an alkyl substituted tin amide. 
     
     
       10. The method of  claim 1 , wherein the tin-containing precursor is selected from the group consisting of tetrakis(dimethylamino) tin, tetrakis(ethylmethylamino) tin, N 2 , N 3 -di-tert-butyl-butane-2,3-diamino-tin(II), and 1,3-bis(1,2methylethyl)-4,5-dimethyl-(4R, 5R)-1,3,2-diazastannolidin-2-ylidine. 
     
     
       11. The method of  claim 1 , wherein the tin-containing precursor is tetrakis(dimethylamino) tin. 
     
     
       12. The method of  claim 1 , wherein the depositing comprises purging a process chamber housing the semiconductor substrate with an inert gas between the sequential exposing of the tin-containing precursor and the oxygen-containing precursor. 
     
     
       13. The method of  claim 12 , wherein the deposition of SnO 2  layer is performed at a process parameter that maintains each of the tin-containing precursor and the oxygen-containing precursor independently in a gaseous phase. 
     
     
       14. The method of  claim 13 , wherein the process parameter is a temperature of the process chamber that is between about 20° C. and about 500° C. 
     
     
       15. The method of  claim 13 , wherein the process parameter is a flow rate at which each of the tin-containing precursor and the oxygen-containing precursor independently is flowed between about 10 sccm and about 10,000 sccm. 
     
     
       16. The method of  claim 1 , wherein the oxygen-containing precursor is selected from the group consisting of ozone, water, oxygen, hydrogen peroxide, and NO. 
     
     
       17. The method of  claim 1 , wherein each of the tin-containing precursor and the oxygen-containing precursor is independently combined with a carrier gas, the carrier gas being selected from the group consisting of helium, argon, and nitrogen. 
     
     
       18. The method of  claim 1 , wherein the deposition of SnO 2  layer is performed using at least one of chemical vapor deposition process, atomic layer deposition, or any combination thereof.